Easy-to-miss radar boxes give police heads up on where speeders have been

Since 2007, Manchester has been deploying two radar devices called Speed Sentry that count vehicles and record their speeds as they pass by.

About the size of a case of beer, the devices are easy for drivers to miss, but Speed Sentry won't miss any vehicle within about 500 yards of its location. And unlike speed board trailers, which flash a vehicle's speed in an obvious effort to alert the driver, each 18-inch-square, 12-inch-deep Speed Sentry box is mounted on the metal post beneath a stop sign.

Although Sentry boxes don't do more than tally traffic volume and record speeds - they can't report a vehicle's make, model or color, and they can't tell who is driving or even get a license plate number - police can use the information that is collected to determine the best times and locations to catch speeders.

"It doesn't do us any good to have someone in a cruiser in a neighborhood at 3 in the afternoon if the highest volume of speeding cars go through at 10 in the morning," said Lt. Maureen Tessier, Manchester police spokeswoman.

Similar devices are also in use in Concord, Nashua, Londonderry and Laconia.

Here's how the process works: Police receive calls, letters or emails from residents complaining about speeders along their street. Police mount a Speed Sentry on a stop-sign post in the area. Data is collected over a few days, downloaded, and fed into a program at police headquarters.

Officials then analyze the results and look for patterns. If they can isolate specific times when speeding is at its worst, they can post a cruiser accordingly.

Instead of a police officer waiting all day to write seven tickets, police can use the radar information to patrol for two hours and write the same number of tickets, Tessier said.

"It generates a nice report," said Tessier. "Very easy to review, broken down by hours, days and locations."

Each Speed Sentry device costs about $4,000. Manchester's were purchased in 2007 by then-Lt. (now Capt.) Jon Hopkins of the Traffic Division.

The signs are rotated to various locations every few days. They were most recently deployed in Manchester near the intersections of Platts Avenue and Candia Road, and Kelley and Kimball streets.

Tessier said the units can flash like a speed board, if desired. "There's also a stealth mode," she said. "That's when the lights are turned off, and it just records data on number of cars and how fast they are going. When the speed is being shown, people have a tendency to slow down as they approach it. When it's off, you get a more accurate picture of how traffic is moving through the area."

Tessier said the units can help police determine whether a neighborhood needs a stop sign or drivers are ignoring one already in place.

"We'll get requests from the Traffic Division asking us to set one up," said Tessier. "Again, if there's already a stop sign there, it doesn't record who is going through the sign, just whether anyone is (not stopping) based on the speed of the vehicle. It's just collecting data."

She said the units have a range of 500 yards, so the speed of a car driving toward a stop sign can be detected from that far away and measured right up to the sentry position on the signpost.

"Because of the range they have, they can monitor speed of cars a good distance away," said Tessier. "If they are on a stop sign, we might not be watching how well the sign works. It might just have been the easiest spot to set one of them up."

The data collected has directly led to speed enforcement efforts in specific locations in the Queen City.

"One area was South Mammoth Road," said Lt. Jim Flanagan of the Traffic Division. "We received complaints of people speeding along that area, set up the Sentry boxes, and when we looked at the numbers decided to allocate resources, when available, to that location for enforcement. We took a similar approach after data was collected along River Road."

Flanagan said he couldn't directly attribute speeding fines or traffic violations issued in an area to the fact that a Sentry box had been set up there prior to conducting enforcement activities.

"We don't assess or follow up with how many tickets were generated because sometimes just the presence of a cruiser and officer in an area is enough to get people to slow down," said Flanagan. "That's a success, without a fine being issued."

Manchester isn't the only community using such devices. Nashua police deploy a StealthStat device to monitor neighborhood traffic and are happy with the results.

"We only have one right now, but we're looking to purchase two more," said Nashua police Capt. Bruce Hansen of that city's Traffic Division. "We set it up for three or four days at a time. If drivers can see their speed, your data can be skewed. Sometimes they speed up just to see how high they can get the numbers to go. One time, a kid stopped to throw a baseball near our speed board to see how fast he could throw it."

StealthStat information has been useful, Hansen said.

"West Hollis Street was one area that generated some staff time," said Hansen. "We looked at times in the day with the highest number of cars, then put an officer in place."

Concord also has two devices.

"They are used for counting cars and measuring speed only," said Concord Lt. Tim O'Malley. "They don't collect data on the drivers, the makes and models of the vehicles, or anything else."

"It utilizes two tubes that stretch across the road," said Londonderry police Lt. Tim Jones. "The tubes attach to a box that is usually chained to a telephone pole, and when cars pass over, it records the numbers and speed of passage. We can use the data to see if the area is in need of traffic enforcement. We generally only use it when we receive a complaint about speeding. We don't put the device out too often because of the wear and tear on the hoses."

Laconia Detective Sgt. Scott Roy said his department has one unit it regularly deploys to collect traffic statistics.

New Hampshire isn't the only state using stealth radar boxes. Calls to police barracks in Burlington, Vt., Portland, Maine, and Framingham, Mass., confirmed they are deployed in those states, along with North Haven, Conn. Annual department reports posted online show they are also used in Ohio, North Carolina and Arizona.

"We have one StealthStat unit," said Framingham Police Chief Steven Carl. "We usually attach it to a telephone pole, then if the data we receive points to a problem, we'll assign an officer to that area."